5 changed files with 145 additions and 78 deletions
@ -0,0 +1,102 @@
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package parser |
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import ( |
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"bytes" |
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"io" |
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"strings" |
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"asciigoat.org/core/lexer" |
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) |
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// TextParser is a generic text parser.
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type TextParser struct { |
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*lexer.Reader |
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pos lexer.Position |
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} |
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// Init initializes the [TextParser] with a non-nil [io.Reader].
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func (p *TextParser) Init(r io.Reader) { |
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switch { |
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case p == nil || r == nil: |
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panic("invalid call") |
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case p.Reader != nil: |
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panic("parser already initialized") |
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default: |
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p.Reader = lexer.NewReader(r) |
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p.pos.Reset() |
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} |
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} |
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// InitBytes initializes the [TextParser] with a byte array
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func (p *TextParser) InitBytes(b []byte) { |
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p.Init(bytes.NewReader(b)) |
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} |
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// InitString initializes the [TextParser] with a byte array
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func (p *TextParser) InitString(s string) { |
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p.Init(strings.NewReader(s)) |
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} |
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// Discard shadows [lexer.Reader]'s, and takes in consideration
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// new lines on the discarded data when moving the position
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func (*TextParser) Discard() { |
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// TODO: consider new lines
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panic("not implemented") |
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} |
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// Emit returns the accepted text, its position, and
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// moves the cursor position accordingly
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func (p *TextParser) Emit() (lexer.Position, string) { |
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pos := p.pos |
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s := p.Reader.Emit() |
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// TODO: consider new lines
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p.pos.StepN(len(s)) |
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return pos, s |
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} |
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// Step discards what's been accepted and increments the
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// position assuming they all increment the column counter
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func (p *TextParser) Step() { |
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s := p.Reader.Emit() |
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p.pos.StepN(len(s)) |
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} |
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// StepLine discards what's been accepted and moves then
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// position to the beginning of the next line
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func (p *TextParser) StepLine() { |
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p.Reader.Discard() |
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p.pos.StepLine() |
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} |
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// Position returns the position of the first character
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// of the accepted text
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func (p *TextParser) Position() lexer.Position { |
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return p.pos |
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} |
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// AcceptNewLine checks if next is a new line.
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// It accepts "\n", "\n\r", "\r" and "\r\n".
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func (p *TextParser) AcceptNewLine() bool { |
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r1, _, err := p.ReadRune() |
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switch { |
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case err != nil: |
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return false |
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case r1 == '\n': |
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p.AcceptRune('\r') |
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return true |
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case r1 == '\r': |
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p.AcceptRune('\n') |
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return true |
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default: |
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p.UnreadRune() |
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return false |
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} |
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} |
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// AcceptRune checks if next is the specified rune
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func (p *TextParser) AcceptRune(r rune) bool { |
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return p.Accept(func(r2 rune) bool { |
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return r == r2 |
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}) |
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} |
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